82 REPORT—1863. 
interposition of paper, influences the result. Small-arm cartridges which have 
auswered best are composed of three layers of flat woven gun-cotton with 
paper interposed. For the small-bore long range rifles used in England, the 
cartridges most suitable may be those represented at Pl. II. fig. 3, the precise 
dimensions of them being fixed experimentally. On the 4th and 5th of 
July 1863, there was a preliminary trial at Manchester, during which it was 
found that no distortion of the projectiles ensued even when the proper 
conditions of charge were departed from by using too heavy charges. 
e. Application of gun-cotton to purposes of mining.—Gun-cotton is more 
appropriate to this use than gunpowder, which it surpasses in proportion as 
the mass to be blasted is more compact. Assuming a solid rock to be blasted, 
and that the proper condition of charge together with the proper distribution of 
holes have both been heeded, the relative proportions of gun-cotton and of 
gunpowder for producing an equal effect are 1 gun-cotton to 6-274 gunpowder 
(weight by weight), whilst the relative proportions for wall-blasting (masonry) 
are 1 gun-cotton to 2:25 gunpowder ; however, here the point must be noted, 
that when these experiments were performed the best shape of charge had 
not been determined. According to experiments more recently conducted, the 
form of charge for blasting which best answers is that of a hollow twisted rope, 
according to sample ; the operation of charging is rendered thus very easy and 
safe—wooden tamping-rods being used until the charge is covered. Accord- 
ing to repeated experiments, the strongest friction of gun-cotton between 
stone is unattended with the slightest danger. Yor large charges, it is to be 
remembered that complete ignition is more difficult than the complete ignition 
of large powder charges; to accomplish this result satisfactorily for mining- 
purposes, it is indispensable to fasten up the gun-cotton in tightly closed 
vessels—which afford the necessary resistance, not yielding until the whole mass 
of gun-cotton has become ignited. Experiments have proved that little barrels 
with strong hoops answer best. The proper construction of these restraining 
cases can be learned experimentally from models, when it will be remarked 
that no smoke results from explosion, and very little fire is seen. 
As a charge for hollow projectiles, gun-cotton substituted for gunpowder 
will produce similar effects ; but then the space of shell is only partly filled, 
even when the bursting powder charge is raised to its maximum. An in- 
creased charge of gun-cotton may be employed with advantage, which thus, 
in comparison with gunpowder, will give an additional effect, partly referable 
to additional material used, and partly to the occurrence of a more rapid ex- 
plosion. 
With projectiles having very small holes for filling, the accompanying 
samples were used, because of the ease with which filling could be conducted. 
When projectiles with cylindrical bore, capable of being thrown open, have 
to be filled, it would be advisable to insert cylindrical charges of gun-cotton 
previously compressed. A soft layer of felt is recommended to be laid in- 
teriorly against the base of the projectile—though this precaution does not 
seem to be imperative, no premature bursting having taken place in the 
course of any experiments, 
f. Application to fuse-purposes.—For fuses gun-cotton is woven (according 
to pattern given), then steeped in saltpetre and covered with a jacket of india- 
rubber. In this manner the progress of combustion is rapid (over 30 feet 
per second) ; the line will bear considerable pressure, and may even be folded 
crossways without fear of the fire leaping from one fold to the other. 
If ordinary gun-cotton thread be fired in a train loosely, ignition is very 
slow, about 1 foot per second. 
